Mapping of metal rust textures on UV sphere
Here is some more explanations about what I proposed in the comments.

The changes in the nodes setting:


All come from 'generate'
Texture nodes are set to 'box'
A blend is tuned to avoid to see the 'box borders' (maybe, you should prefer to link them all with a single value)
The UV map is removed from the normal map node to keep coherency regarding the texture




So when the material is changed to that:



But the blending of the 'box' mode looses a bit of the quality.

Edit: some explanations following the comments

The sphere cannot be unwrapped equally (respecting model vs. UV map proportions) without seams.

But if you have seams, that will be visible at the junction on the 3D model (even if we have seen a solution here Realistic Rusty Chain, the problem is your texture is repainted so is no more generic).

So we don't want seams. But without seams no respect of proportions...

The box mapping (as I imagine it works):

It is a cube envelop projected on the surface. And... that makes seams.
But we have the ability to use the blend factor, which is some way extends the envelop so that parts overlap but are blended.

So all seems to be good... except the point I mentioned before: we loose a bit of quality due to this blending.